#Question id: 14243
#Section 5: Bioprocess Engineering and Process Biotechnology
A tubular-bowl centrifuge is used to concentrate a suspension of genetically-engineered yeast containing a new recombinant protein. At a speed of 12 000 rpm, the centrifuge treats 3 l broth min-1 with satisfactory results. It is proposed to use the same centrifuge to separate cell debris from homogenate produced by mechanical disruption of the yeast. If the average size of the debris is one-third that of the yeast and the viscosity of the homogenate is five times greater than the cell suspension, what flow rate can be handled if the centrifuge is operated at the same speed? _____________________
#Question id: 14244
#Section 5: Bioprocess Engineering and Process Biotechnology
Ethanol is produced by anaerobic fermentation of glucose by Saccharomyces cerevisiae. For the particular strain of S. cerevisiae employed, the maintenance coefficient is 0.18 kg kg- 1 h- 1, Yxs is 0.11 kg kg-1, YPX is 3.9 kg kg-1 and µmax is 0.4 h-1. It is decided to investigate the possibility of using Zymomonas mobilis bacteria instead of yeast for making ethanol. Z. mobilis is known to produce ethanol under anaerobic conditions using a different metabolic pathway to that employed by yeast. Typical values of Yxs are lower than for yeast at about 0.06 kg kg-1; on the other hand, the maintenance coefficient is higher at 2.2 kg kg -1 h -1. Ypx for Z. mobilis is 7.7 kg kg-l; µmax is 0.3 h- 1. From stoichiometry, what is the maximum theoretical yield of ethanol from glucose
#Question id: 14245
#Section 5: Bioprocess Engineering and Process Biotechnology
Ethanol is produced by anaerobic fermentation of glucose by
Saccharomyces cerevisiae. For the particular strain of S. cerevisiae employed,
the maintenance coefficient is 0.18 kg kg- 1 h- 1, Yxs is
0.11 kg kg-1, YPX is 3.9 kg kg-1 and µmax is 0.4 h-1. It is decided to investigate the possibility
of using Zymomonas mobilis bacteria instead of yeast for making ethanol. Z.
mobilis is known to produce ethanol under anaerobic conditions using a
different metabolic pathway to that employed by yeast. Typical values of Yxs
are lower than for yeast at about 0.06 kg kg-1; on the other hand,
the maintenance coefficient is higher at 2.2 kg kg -1 h -1.
Ypx for Z. mobilis is 7.7 kg kg-l; µmax is 0.3 h- 1. Y’PS
is maximum and equal to the theoretical yield when there is zero growth and all
substrate entering the cell is used for maintenance activities. If ethanol is
the sole extracellular product of energy-yielding metabolism, calculate mp for yeast?
#Question id: 14246
#Section 5: Bioprocess Engineering and Process Biotechnology
A steam steriliser is used to sterilise liquid medium for
fermentation. The initial concentration of contaminating organisms is 108
per litre. For design purposes, the final acceptable level of contamination is
usually taken to be 10-3cells; this corresponds to a risk that one
batch in a thousand will remain contaminated even after the sterilisation
process is complete. For how long should 1 m3 medium be treated if
the temperature is 80⁰C ________________.10^6
#Question id: 14247
#Section 5: Bioprocess Engineering and Process Biotechnology
A steam steriliser is used to sterilise liquid medium for fermentation.
The initial concentration of contaminating organisms is 108 per
litre. For design purposes, the final acceptable level of contamination is
usually taken to be 10-3cells; this corresponds to a risk that one
batch in a thousand will remain contaminated even after the sterilisation
process is complete. For how long should 1 m3 medium be treated if
the temperature is 121⁰C ________________.
#Question id: 14248
#Section 5: Bioprocess Engineering and Process Biotechnology
A steam steriliser is used to sterilise liquid medium for
fermentation. The initial concentration of contaminating organisms is 108
per litre. For design purposes, the final acceptable level of contamination is
usually taken to be 10-3cells; this corresponds to a risk that one
batch in a thousand will remain contaminated even after the sterilisation
process is complete. For how long should 1 m3 medium be treated if
the temperature is 140⁰C ________________.